Process for the manufacture of coatings



Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE.

WILHELM HEINRICH OTTO JOHANNES SOHEIBER, OF LEIPZIG, GERMANY, ASSIGNOB OI ONE-HALF TO THE FIRM BAKELITE GESELLSCHAIT M. B. 11., OF ERKNER B/BERLIN, GERMANY, AND ONE-HALF TO THE FIRM CHEMISCHE FABRIKEN DR. JOACHIM WIERNIK 8:, 60., L G., OF BERLIN-WAIDMANNSLUST, GERMANY PROCESS FOR THE MANUFACTURE OF COATINGS No Drawing. Application med October 15, 1928,

It is known that paints whose bases are fatty oils and oil-lacquers whether they are put on in a transparent film or in combination with pigments, including filling materials of all kinds, are destroyed in a certain time if they are put on not in a single layer but if several coats areplaced one on the other. The destroying factors become noticeable especially in outside work which is a considerable disadvantage since the intended protection of numerous important and valuable objects is more or less lost because of the insuflicient durability of the protecting layers. Usually one renews the coatings after a lapse of a certain time but without being sure that the coatings have really the protective action during the periods of renewals.

As destroying factors light, variations in temperature, water and certain constituents of the air, especially oxygen must be considered. Naturally it is not possible to devise any means by which the influence of the air can be eliminated. Such a procedure would not be desirable, even if it could be really accomplished, because the drying of the coatings whose bases are fatty oils and oil-lacquers requir s the direct action of oxygen. Accordingly it is important that the action of the oxygen should be even increased; for this purpose the so-called siccatives are added to the coatings in a known manner because otherwise the drying of the coatings would not be accomplished as quickly as is desirable for economical reasons.

But it is a fact that the favourable action of the siccatives which it is important not to lose in the beginning, should change after the solidification of the film; for the fatty oils are not only dried by oxidation, but, as has been proved by numerous experiments, they are also decomposed by oxidation-processes. Though this process at first has no considerable detrimental effect, yet it assumes dangerous proportions in the course of time and must be considered in the later stages as a main factor, since the destruction of the films gradually increases. Thus it is clear that the elimination of the action of the siccatives in this stage must influence the Serial No. 812,750, and in Germany October 19, 1927.

durability of the coating in a favourable manner.

It is known that besides the so-called positive catalysis caused by the siccatives, that is to say an activation of oxygen, there can be produced also a so-called negative catalysis,

that is to say an elimination of the influence of the oxygen. This action can be produced by a number of substances, i. e. phenols of all kinds, aromatic amines, derivatives of urea, etc. which are included under the name antioxidizers. If one adds such substances to drying fatty oils, then the solidification, which would normally occur within a short time, is delayed for many months or even the action reversed. This action would be observed also if antioxidizers are added simultaneously with the siccatives to the fatty oils. Thus it is possible to reverse or to regulate to a considerable degree the positive catalysis of the siccatives through the addition of negative catalysts. The accomplishment of this phenomen is diflicult because generally it is not possible to allow the antioxidizing action to occur from the beginning, since this must naturally lead to an inadmissible prolongation of the time of drying. Only in the case of wood-oil can one proceed in this manner, because the drying of these oils does not require a preceding variation in any important complex through the ac tion of oxygen. On the contrary with all other drying or demi-drying fatty oils such oxidizing conversion is inadmissible. For this reason it is not possible to omit the action of the siccatives in the utilization of pihese products as binders or as basis for the In an application, $erial No. 452,137, filed May 13, 1930, divided from this application, it is proposed to meet the difficulties arising from the di'rect, simultaneous use of the antioxidizers in the manner that the films, obtainable in the usual way and with the usual products, are after-treated with suitable solutions of the antioxidizers, after the regular normal drying.

According to the present invention, however, the antioxygenizing means are not to be added in a directly active form, but in an indifferent state. This indifference may be reached by means, the effect of which is gradually reversed so that an increasing efiiciency takes place as the film ages. If there is added to boiled linseed oil a phenol, i. e. alpha-naphtol, the drying of the film is hindered, but if the alpha-naphtol is used in the form of its lead salt, the boiled linseed oil is dried quite normally. In consequence of the unhindered efiect of the siccative not only the formation of the film can proceed but also the products of decomposition which are obtained simultaneously with the formation of the film may be formed. These products (carbonic acid, formic acid, acetic acid, etc.) have partially the character of acids and decompose gradually the lead salt i. e. of the alpha-naphtol, whose acid qualities are not very distinct. The consequence is a gradual increase of free naphtol in the film which fil quickly prevents the further decomposition.

A special advantage of the process lies in the fact that the quantity of lead phenolate is not limited. In this manner it is possible to obtain almost any desired prolongation of the durability of the film.

Besides the lead salts of the different phenols there may be applied other phenolates, i. e. zinc, barium-, magnesiumetc.- compounds.

Instead of alpha-napthol there may be applied any desired uni or polyvalent phenols with one or more nuclei or such phenol ethers of polyvalent phenols containing a hydroxyl group.

What I claim and desire to secure by Letters Patent of the United States is:

1. A process for the preparation of substances to be used as coatings having drying fatty oils or oil-lacquers as basis, comprising adding to said basis as antioxidizers phenolates which are first indifferent when said substances are just applied as a coating film on a support and which are slowly decomposed into active antioxidizers during the ageing and drying of said film under the action of chemical agents acting in said drying film.

2. A process for the preparation of substances to be used as coatings having drying fatty oils or oil-lacquers as basis, comprising adding to said basis as antioxidizers lead salts of alpha-naphtol, which are first indifferent when said substances are just applied as a coating film on a support and which are slowly and gradually decomposed into active antioxidizers during the ageing and drying of said film, under the action of chemical agents of acid character acting in said drying 3. A process for the preparation of substances to be used as coatings having drying fatty oils or oil-lacquers as basis, comprising adding to said basis as antioxidizers lead salts of alpha-naphtol, which are first indifferent when said substances as a coating film on a support and which are slowly and gradually decomposed into active antioxidizers during the ageing and drying of said film, under the action of chemical agents of acid character acting in said drying film, thus producing slowly in said film a gradual increase of free naphtol which prevents the further decomposition of said lead salts.

4. A process for the preparation of a substance to be used as coating having drying boiled linseed oil as basis, comprising adding to said oil as antioxidizer a phenolate which is first indifferent when said substance is just applied as a coating film on a support and which becomes slowly and gradually active as antioxidizers as said film ages and dries under the action of acid agents in said drying m. 5. A substance to be used as coating having drying fatty oils or oil-lacquers as basis, to which is added as antioxidizers phenolates which are first indifferent when the substance is just applied as a coating-film on a support and then become gradually active as antioxidizers during the ageing and drying of said film under the action of chemical agents of acid character.

6. A substance to be used as coating having drying boiled linseed oil as basis, to which is added as antioxidizers a lead salt of alphanaphtol which is indifferent at first when said substance is applied as a coating film on a support and which decomposes slowly into active antioxidizer during the ageing and drying of said film under the action of said agents.

WILHELM HEINRICH OTTO JOHANNES SCHEIBER.

are just applied 

